The present disclosure relates to semiconductor memories. More specifically the present disclosure relates to flash memories and a memory card system including the same.
Multimedia cards (MMCs) are kinds of communication media and data storage units generally used in low-priced devices intended for normal users. MMCs are usually designed to be operable in various applications, such as smart phones, cameras, personal data assistants (PDAs), digital recorders, MP3 players, pagers, and so forth. MMCs are nowadays regarded as being characterized by high portability and good performance with low prices.
FIG. 1 is a schematic block diagram of a general multimedia card.
Referring to FIG. 1, the MMC 20 includes an MMC controller chip 22 and a flash memory 24. The MMC controller chip 22 and the flash memory 24 are each constructed as independent chips. In other words, the MMC 20 is composed of two chips. The flash memory 24 is formed in a NAND type that is well known in this art. The MMC controller chip 22 functions to conduct interfacing operations between a host 10 and the flash memory 24.
As the MMC 20 is organized of two chips, the cost is increased for fabricating the MMC 20. Further, data security would be worse due to exposure of data that is transceived between the MMC controller chip 22 and the flash memory 24.
With the object of solving those problems, a way of fabricating a one-chip MMC 40 has been recently proposed, as illustrated in FIG. 2. In the MMC 40, an MMC controller 44 and a flash memory 46 are integrated in a single memory chip 42. Since the one-chip MMC 40 can be structured without pads and signal lines for connecting the MMC controller 44 with the flash memory 46, it makes the chip area smaller and can be produced at a lower cost. Moreover, without exposure of data transferred between the MMC controller 44 and the flash memory 46, it enhances the data security.
Generally, wide-scope applications and diverse users usually require MMCs that are variable in storage capacities. If a number of the flash memories 24 are provided in the MMC 20 shown in FIG. 1 and changes made to a firmware of the MMC controller 22, a capacity of the MMC 20 may be variable.
It is not easy, however, for the MMC 40 to vary the storage capacity of the flash memory. To change a storage capacity of the flash memory, it is required to fabricate a memory chip using newly designed circuit patterns and providing plural memory chips to the MMC. In organizing an MMC with pluralities of memory chips, there needs to be considered an interface pattern between a host and the MMC.